There is a popular question about inputting Unicode characters:
How do you type Unicode characters using hexadecimal codes?
And an accepted answer:
The problem is that the solution provided in the accepted and highly upvoted answer simply does not work. To be more specific, the answer suggests inputing character using Alt + decimal code (on numpad), which works only in rare case, namely it works for ANSI (ddd = 0-255) characters, or, if the number is preceded by zero, like 0dddd, it inputs "dddd modulo 256"-th character from selected codepage. Which obviously does not solve the general problem of inputting unicode characters by its ordinal (which was the question about).
The only Windows app (I tested on windows 10) where the solution worked for me was Word - it worked there as described. Everywhere else it did not work, and despite I am highly experienced user it took significant time to resolve the confusion caused by the answer. I imagine for people with less experience it is extremely misleading, and many people are searching this problem to input e.g. some math symbols, etc.
So the only way that the answer would make sense - it should state in the first line put in bold, where and how exactly the solution may work. Comments under the question note these problems, but the answer itself has not changed and stays highly misleading.
What should be made about it?
And what is usually made in such situations?
I could try edit the answer, but I can't test all the cases (Os versions/ apps) to give concrete answer, and I don't know what worked for them (maybe it worked somewhere, but it is not stated in the answer).